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3: Paeds Y3/4 - Paediatrics [15] > [42] Down's Syndrome > Flashcards

[42] Down's Syndrome Flashcards

1
Q

What is Down’s Syndrome also known as?

A

Trisomy 21

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2
Q

What is meant by Trisomy 21

A

The patient has three copies of chromosome 21

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3
Q

Is the extra copy of 21 a full or partial copy?

A

Can be either

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4
Q

How common is Down’s Syndrome compared to other autosomal trisomies?

A

It is the most common

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5
Q

How common is Down’s Syndrome in terms of causes of severe learning difficulties?

A

It is the most common

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6
Q

What can the extra chromosome 21 occur as a result of?

A

Non-disjunction, translocation or mosaicism

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7
Q

What is the most common cause the extra chromosome 21?

A

Meiotic nondisjunction

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8
Q

How many cases of Trisomy 21 are due to meiotic nondisjunction?

A

94%

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9
Q

What happens in meiotic nondisjunction?

A

Chromosome 21 fails to separate leaving one gamete with 2 and on game with none

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10
Q

In order for Down’s Syndrome to occur in meiotic non-disjunction, which gamete must be fertilised?

A

The one with two chromosome 21 copies

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11
Q

What increases the likelihood of meiotic non-disjunction in the maternal gamete?

A

Increasing maternal age?

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12
Q

Can meiotic non disjunction occur in spermatogenesis?

A

Yes

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13
Q

What does meiotic non-disjunction during spermatogenesis mean?

A

That the abnormal gamete can be of paternal origin

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14
Q

What percentage of Down’s Syndrome cases are caused by translocation?

A

5%

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15
Q

What is a Robertson translocation?

A

When the extra chromosome 21 is joined onto another chromosome

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16
Q

Do all people with Robertson translocation present with symptoms?

A

No, some are phenotypically normal carriers

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17
Q

What test is recommended due to the ability for phenotypically normal carriers to exist?

A

Parental chromosomal analysis

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18
Q

What percentage of Down’s Syndrome is caused by mosaicism?

A

1%

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19
Q

What is mosaicism?

A

Where some cells are normal and some have trisomy 21

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20
Q

How does mosaicism usually arise?

A

Zygote is chromosomally normal but non-disjunction occurs during mitosis

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21
Q

What is sometimes the case in patient with mosaicism forms of trisomy 21?

A

The phenotype is milder

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22
Q

What is the main risk factor for development of Down’s syndrome?

A

Older mother

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23
Q

What are the main signs of Down’s Syndrome?

A
  • Characteristic craniofacial appearance
  • Short neck
  • Single palmar crease
  • Incurved and short 5th finger
  • ‘Sandal gap’ between 1st and 2nd toes
  • Hypotonia
24
Q

What are the characteristic craniofacial features of Down’s Syndrome?

A
  • Round face
  • Flat nasal bridge
  • Upslanted palpebral fissures
  • Epicanthic folds
  • Brushfield spots in iris
  • Small mouth and protruding tongue
  • Small ears
  • Flat occiput and third fontanelle
25
How is Down's Syndrome often picked up?
Antenatal screening
26
What are all pregnant women offered with regards to antenatal screening for Down's Syndrome?
- Blood biochemical marker tests | - USS to look for nuchal thickening
27
What are women with an identified increased risk offered?
Amniocentesis
28
What does amniocentesis allow?
Checking of fetal karyotype
29
What are becoming increasingly available to allow early detection of Down's Syndrome in pregnancy?
Non-invasive karyotyping techniques
30
What should happen if there is clinical suspicion of Down's Syndrome following birth?
A senior paediatrician should discuss this with the parents
31
How should a post-birth diagnosis of Down's Syndrome be confirmed?
Chromosome analysis
32
What technique can be used to analyse chromosomes after birth?
Interphase FISH
33
What is another trisomy that should be considered when diagnosing Down's Syndrome?
Trisomy 18
34
What is trisomy 18 also known as?
Edward's Syndrome
35
What other conditions should be considered as differentials for Down's Syndrome?
- Multiple X Syndrome | - Zellweger syndrome
36
What further testing should children with Down's Snydrome be referred for following birth?
- Detailed cardiac assessment - Hip ultrasound - Audiology
37
What is the role of a clinical geneticist in the management of Down's Syndrome?
Genetic counselling
38
What may be useful to help parents cope with their child being diagnosed with Down's Syndrome?
Access to support organisations e.g. Down Association
39
In the long-term how are patients with Down Syndrome continued to be managed?
- Follow-up by MDT - Physiotherapy - Annual TFT - Audiology and ophthalmic assessment every 1-2 years
40
What is the main cause of early death in Down's Syndrome?
Congenital cardiac diseases
41
Excluding congenital cardiac diseases, what is the life expectancy of a person with Down's Syndrome?
Well into adult life
42
What do most patient's with Down Syndrome develop by their 40's?
Alzheimer's
43
What is the effect of most patient's with Down Syndrome developing Alzheimer's by their 40's?
Life expectancy is somewhat shortened from average
44
How do the majority of patient's with Down Syndrome live in adult life?
Semi-independently with supervision
45
What congenital diseases are associated with Down's Syndrome?
- Congenital heart defects - Duodenal atresia - Hirschsprung's
46
What percentage of patient's with Down's Syndrome have congenital heart defects?
40%
47
What percentage of patient's with Down's Syndrome have Hirschsprung's?
~1%
48
What later medical problems may a person with Down's Syndrome be at increased risk of developing?
- Delayed motor milestones - Learning difficulties - Short stature - Increased susceptibility to infections - Otitis media w/ effusion - Visual problems - Increased risk of leukaemia and solid tumours - Acquired hip dislocation - Atlantoaxial instability - Obstructive sleep apnoea - Hypothyroidism - Coeliac disease - Epilepsy - Early onset Alzheimer's
49
What percentage of patient's with Down's Syndrome develop otitis media with effusion?
75%
50
What is the consequence of otitis media with effusion?
Hearing impairment
51
What effect may hearing impairment have on development?
Slow, especially speech
52
What visual impairments may develop in Down's Syndrome?
- Cataracts - Squints - Myopia
53
What percentage of patient's with Down's Syndrome develop cataracts?
15%
54
What percentage of patient's with Down's Syndrome develop myopia?
50%
55
What percentage of patient's with Down's Syndrome develop obstructive sleep apnoea?
50-75%
56
What percentage of patient's with Down's Syndrome develop hypothyroidism?
15%

3: Paeds Y3/4 - Paediatrics [15] (115 decks)

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